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Phosphate-Free Inhibition of Calcium Carbonate Dishwasher Deposits

DOI: 10.1021/acs.cgd.7b01508 DOI Help

Authors: Yuexian Hong (Durham University) , Nathalie Letzelter (Procter & Gamble Newcastle Innovation Centre) , John S. O. Evans (Durham University) , Dmitry S. Yufit (Durham University) , Jonathan W. Steed (Durham University)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Crystal Growth & Design

State: Published (Approved)
Published: January 2018
Diamond Proposal Number(s): 8682

Abstract: This paper reports the characterization of the composition and morphology of mineral formation on glass and plastic (polymethylmethacrylate) substrates in a dishwasher environment and the identification of suitable phosphate-free mineral crystallization inhibitors as environmentally benign candidates to replace the currently used phosphate-containing inhibitor 1-hydroxyethane 1,1-diphosphoric acid (HEDP). Screening of the calcium carbonate crystallization inhibition performance of twenty-eight different compounds resulted in the identification of two phosphate-free, cyclic polycarboxylic acid inhibitors, which were found in combination to be effective replacements. Each inhibitor proved to be highly substrate specific with all-cis-cyclohexane-1,2,3,4,5,6-hexacarboxylic acid (CHHCA) preventing deposition on glass (where calcite is the dominant polymorph) and cis,cis,cis,cis-cyclopentane-1,2,3,4-tetracarboxylic acid (CPTCA) inhibiting aragonite deposition on polymethylmethacrylate (PMMA). When used in combination, these two species prevented all forms of calcium carbonate deposition on both substrate types. The underlying inhibition mechanism and structural requirements of an efficient calcium carbonate inhibitor are also discussed.

Journal Keywords: Calcium carbonate; inhibitor; dishwasher detergent; crystallization

Subject Areas: Chemistry

Instruments: I19-Small Molecule Single Crystal Diffraction